This invention relates to a method for communication between components of a machine which can be used for monitoring operation of a machine and/or for actuating or controlling various aspects of the machine. The invention is particularly but not exclusively designed for use with agricultural machines such as seeders, planters and the like.
Devices for monitoring seeders, planters and the like have previously been proposed, and generally these include sensors or transducers at various locations on the device for detecting various parameters of the operation of the machine. Thus one well known requirement for a sensor is that of detecting seed flow or seed movement. In an air seeder it is often desirable to detect the flow of seeds in an air tube to provide an indication of the rate of flow which can be also used to detect a blockage or zero flow. Further sensors have been provided for detecting the rate of rotation of shafts of the machine either for detecting seed supply rate or for detecting other parameters such as ground speed as detected by rotation of an axle. Yet further sensors have been provided for detecting a level of filling of a supply tank.
Generally the detection apparatus includes a central control unit with a key pad for allowing manual data entry, a display for providing information to the operator and a communication system for communication between the central control unit and the individual sensors. Generally devices of this type have used sensors which are simply switches or transducers which therefore provide a simple detection of a parameter to be detected and transmit a signal to the central control unit on detection of the parameter. Thus the conventional sensor does not include any memory or logic control so that the information is not acted upon or stored at the sensor itself. Such sensors require direct communication from the sensor itself to the control unit thus requiring individual wiring from each sensor to the control unit.
As the monitoring devices of this type become more complex and require more parameters to be monitored, the complexity of such individual wiring arrangements significantly increases cost and installation complication.
In addition to the monitoring function the present invention can also be used in relation to combined monitoring and control functions and also in relation to communication protocols between elements of a control system which does not include any monitoring function.